For packaging and shipping sterile products, such as medical or surgical instruments or items, as for example syringe containing boxes or bags, boxes made of a foamed plastic material are used, being treated together in a sterilizing enclosure with the products being contained therein. A method consists in filling the box with the involved product being as-made and not yet sterile, and then subjecting the whole set to a sterilizing treatment with an appropriate gas, such as EtO (ethylene oxide) in a sealed enclosure. After a given exposure time, up to 75 hours, the gas is vented from the enclosure and substituted with air before the product is extracted from the enclosure. The treated product is thus shipped in its box without any further handling before it reaches its destination.
The gas used for the sterilizing treatment being by nature very toxic as it is to kill any germ, it should be ensured that gas traces do not remain trapped inside the packaging. The implemented treatment procedures are provided so as to give a total safety for the operators and agents in charge of handling the boxes, including when leaving the treatment enclosure.
Foamed plastic material plates are commonly used for manufacturing packaging boxes. Such a material is both light and strong. It could be compared to corrugated cardboard, and has the additional advantage of being durable and more resistant to contamination that the latter.
The expression “foamed plastic material plates” as used herein means plates made of at least two parallel planar sheets maintained spaced apart one from the other by mutually parallel walls. Sheets and walls provide therebetween longitudinal channels referred to as cells in the art. Such plates are obtained through extruding a plastic material being selected depending on the application, such as a polyolefin, through a rectilinear die. Immediately downstream from the extrusion head, the material, still in a plastic condition, passes through sizing plates to fix the plate shape.
Such a plate type is presently widely used and is likely to replace corrugated cardboard for some applications as the one disclosed hereinabove. The standard box is the American box. It comprises a belt with four panels extended on both sides by flaps being folded at right angle for forming the bottom and the top or lid of the box.
In the case of a box to be used for sterilizing treatments, the covering sheets making up the foamed plate are perforated with a multiplicity of holes for providing a gas circulation through the latter during the treatment phase in the enclosure and preventing the latter from building up and forming residual pockets at the end of the treatment upon the gas removing step.
The Applicant has established as a goal to improve the gas circulation through the box when flaps are folded at right angles and the box is closed ready to be directly shipped after being treated in the gas sterilizing enclosure.